1. Field of the Invention
The present invention relates to apparatus operable to isolate a load from the base device to which it is attached and more particularly to utilize a novel suspension and damping concept to provide vibration isolation between the load and the base in translational degrees-of-freedom while increasing the stiffness for rotational degrees-of-freedom.
2. Description of the Prior Art
Although load vibration isolation has application in various fields including automotive, machinery and the like, the present invention is described in the environment of launch vibration isolation of a payload or satellite, mounted on a launch vehicle. Isolation is achieved by placing elastic members between the launch vehicle and the payload and then placing damping members across the elastic members to provide damping. In such applications, it is difficult to support the payload at the center-of-gravity allowing translational motion to be cross-coupled into rotational motion causing the payload to sway. This rotation is undesired since, for payloads such as inertial measurement units (IMU's) their alignment must be maintained with respect to the vehicle, and, for satellites, the sway uses up the available "rattle space" between the satellite and the inside of the aerodynamic faring. Accordingly, it is advantageous to stiffen the rotational degrees-or-freedom while softening the translational degrees of freedom.
In the prior art, the payload has been supported by independent spring/damper units, typically mounted at various angles to provide the proper stiffness in each degree-of-freedom. In such a configuration, each spring/damper unit operates independent of the others. Other approaches have been to distribute the stiffness and damping around the base of the payload. The rotational stiffness of these isolation systems are limited by the center-of-gravity offset of the payload and the diameter across the base (mounting circle) and, while changing the angles of the spring/damper units allows some freedom in selecting the proper stiffness, the results are limited.